问题 选择题

已知地球半径R、自转周期T、地球表面重力加速度g,则地球同步卫星的环绕速度为

A.

B.

C.

D.

答案

答案:C

题目分析:地球表面万有引力提供重力即,可得,地球同步卫星周期等于地球自转周期,而同步卫星的向心力有万有引力提供即可得同步卫星半径,则卫星线速度,对照选项C对。

阅读理解

We recycle(回收利用)rubbish, so why not language? Recycling language means using vocabulary that you have learnt before again and again. However, unlike rubbish that piles up(堆积)in our environment. if we do not recycle language, we simply forget it. So how do you recycle language?

There are basically three ways to do it. The first is through reading. Go back to your favourite articles and read them once more. Just reread them and do not worry about each vocabulary item. If there are some that you are not sure about, make a guess and you will probably guess right. The second way to recycle is through writing. Look at some of your favourite articles and write either a short paragraph or a few sentences in your own words. After you have done this a few times, go back and read through what you have written, checking vocabulary functions. Don’t worry if you have made mistakes. That’s how you learn. The third way to recycle language is by having an imaginary chat with yourself about your favourite articles at home. You can pretend there is someone with you who speaks English and tell him what you are thinking about or how you feel.

( )12. According to the passage, recycling language means ______.

A. repeating vocabulary at times    B. revising vocabulary at a proper time

C. learning new vocabulary as much as possible

D. using vocabulary that we have learnt very often

( )13. If we recycle language, it may ______.

A. be kept in our mind                   B. be forgotten easily

C. pile up in our environment            D. disappear from our mind soon

( )14. Which of the following is NOT mentioned in recycling language?

A. Reading.        B. Listening.       C. Writing.        D. Speaking.

( )15. Which of the following is probably the best title of the passage?

A. Why to Recycle Language              B. How to Learn Vocabulary

C. How to Recycle Language              D. Why to Learn Vocabulary

多项选择题